These studies will determine whether 16 weeks of daily treatment with cDNA derived human growth hormone produces as increase in skeletal muscle mass and improvement in muscle strength and function in 10 ambulatory men with myotonic dystrophy, 10 male controls with facioscapulohumoral dystrophy and 10 non-obese, aged-matched normal men. If positive results are obtained, a large scale, double-blind, randomized trial in myotonic dystrophy will be begun.